Amount Of H2O2 Research Articles

The preparation of Ag@AgCl photocatalytic material based on the photocatalysis material CA+ and degradation of tetracycline

In this paper, the photocatalysis material CA+, which uses calcium alginate as carrier and cetyltrimethylammonium bromide as surfactant, was studied. The morphology and structure of the prepared CA+ were characterised by SEM, TEM, FT-IR and Raman spectroscopy. The surface electrical properties and stability of the catalytic materials were evaluated by Zeta potential and cycling performance measurements, and the data were analyzed and processed according to the principle of degradation kinetics. The results show that Ag@AgCl Nanoparticles are distributed on the cross-linked structure of CA in the form of clusters. The prepared CA+ photocatalyst material has good adsorption performance and photocatalytic activity for tetracycline (TC). Temperature has a significant effect on the degradation of TC by photocatalytic materials. The photocatalytic degradation rate is the highest at 40 °C, and the photocatalytic reaction rate was 0.08276 min−1. The photocatalytic degradation process at different temperatures conforms to the quasi first-order reaction kinetics. Adding a certain amount of H2O2 can produce more active species O2 −. The photocatalytic material has the advantages of good stability, short photocatalytic degradation time, high catalytic efficiency, and can be used for the degradation of actual tetracycline polluted wastewater.

Modulation of Molybdenum oxidation state via Catalytic-oxidation

Molybdenum (Mo) is a promising metal contact material to replace tungsten due to its low electrical resistivity in sub-3 nm next-generation semiconductor processes. However, the high dissolution rate of Mo during the chemical mechanical planarization (CMP) process limits its practical introduction because it deteriorates surface flatness and consequently causes decisive device failure. Herein, we report a strategy to suppress Mo dissolution by manipulating the oxidation state of Mo film via catalytic-oxidation reaction. Adoption of Fe catalyst under the trace amounts of H2O2 enables the formation of insoluble MoO2 and Mo2O5 phases while minimizing the generation of the soluble MoO3 phase. The dissolution behaviors of Mo at various oxidation states were investigated according to both oxidizer and catalyst concentrations during the CMP process. To identify the detailed dissolution phenomena of Mo, the Gibbs free energies and dissolution kinetics in different Mo oxide phases were validated using density functional theory (DFT) calculation. We successfully confirmed that catalytic-oxidation using Fe ions achieved an enhanced removal rate from 780 to 1500 Å/min, even though the dissolution rate was minimized from 636 to 57 Å/min compared to a single oxidation reaction. We believe that our results, supported by theoretical considerations and experimental results, can elucidate Mo oxidation and dissolution phenomena for application to the advanced semiconductor manufacturing processes.

Lactate oxidase/catalase-displaying nanoparticles efficiently consume lactate in the tumor microenvironment to effectively suppress tumor growth

The aggressive proliferation of tumor cells often requires increased glucose uptake and excessive anaerobic glycolysis, leading to the massive production and secretion of lactate to form a unique tumor microenvironment (TME). Therefore, regulating appropriate lactate levels in the TME would be a promising approach to control tumor cell proliferation and immune suppression. To effectively consume lactate in the TME, lactate oxidase (LOX) and catalase (CAT) were displayed onto Aquifex aeolicus lumazine synthase protein nanoparticles (AaLS) to form either AaLS/LOX or AaLS/LOX/CAT. These complexes successfully consumed lactate produced by CT26 murine colon carcinoma cells under both normoxic and hypoxic conditions. Specifically, AaLS/LOX generated a large amount of H2O2 with complete lactate consumption to induce drastic necrotic cell death regardless of culture condition. However, AaLS/LOX/CAT generated residual H2O2, leading to necrotic cell death only under hypoxic condition similar to the TME. While the local administration of AaLS/LOX to the tumor site resulted in mice death, that of AaLS/LOX/CAT significantly suppressed tumor growth without any severe side effects. AaLS/LOX/CAT effectively consumed lactate to produce adequate amounts of H2O2 which sufficiently suppress tumor growth and adequately modulate the TME, transforming environments that are favorable to tumor suppressive neutrophils but adverse to tumor-supportive tumor-associated macrophages. Collectively, these findings showed that the modular functionalization of protein nanoparticles with multiple metabolic enzymes may offer the opportunity to develop new enzyme complex-based therapeutic tools that can modulate the TME by controlling cancer metabolism.Graphical

2D-imaging of absolute OH and H2O2 profiles in a He–H2O nanosecond pulsed dielectric barrier discharge by photo-fragmentation laser-induced fluorescence

Pulsed dielectric barrier discharges (DBD) in He–H2O and He–H2O–O2 mixtures are studied in near atmospheric conditions using temporally and spatially resolved quantitative 2D imaging of the hydroxyl radical (OH) and hydrogen peroxide (H2O2). The primary goal was to detect and quantify the production of these strongly oxidative species in water-laden helium discharges in a DBD jet configuration, which is of interest for biomedical applications such as disinfection of surfaces and treatment of biological samples. Hydroxyl profiles are obtained by laser-induced fluorescence (LIF) measurements using 282 nm laser excitation. Hydrogen peroxide profiles are measured by photo-fragmentation LIF (PF-LIF), which involves photo-dissociating H2O2 into OH with a 212.8 nm laser sheet and detecting the OH fragments by LIF. The H2O2 profiles are calibrated by measuring PF-LIF profiles in a reference mixture of He seeded with a known amount of H2O2. OH profiles are calibrated by measuring OH-radical decay times and comparing these with predictions from a chemical kinetics model. Two different burst discharge modes with five and ten pulses per burst are studied, both with a burst repetition rate of 50 Hz. In both cases, dynamics of OH and H2O2 distributions in the afterglow of the discharge are investigated. Gas temperatures determined from the OH-LIF spectra indicate that gas heating due to the plasma is insignificant. The addition of 5% O2 in the He admixture decreases the OH densities and increases the H2O2 densities. The increased coupled energy in the ten-pulse discharge increases OH and H2O2 mole fractions, except for the H2O2 in the He–H2O–O2 mixture which is relatively insensitive to the additional pulses.

Concise nanotherapeutic modality for cancer involving graphene oxide dots in conjunction with ascorbic acid.

Cancer cells tend to have higher intracellular reactive oxygen species (ROS) levels and are more vulnerable to ROS-generating therapies such as ascorbic acid (H2Asc) therapy, whose potency has been explored by several clinical trials. However, its efficiency is restricted by the requirement of pharmacologically high local H2Asc concentrations. Here, we show that nitrogen-doped graphene oxide dots (NGODs), which are highly crystalline and biocompatible, can serve as a catalytic medium for improving H2Asc cancer therapy at orally achievable physiological H2Asc concentrations. NGODs catalyze H2Asc oxidation for H2O2 and dehydroascorbic acid generation to disrupt cancer cells by consuming intracellular glutathione (GSH) and inducing ROS damage. This is the first study to demonstrate the direct consumption of GSH using a carbon-based nano-catalyst (NGODs), which further expedites tumor killing. In addition, as in our previous study, NGODs can also serve as a highly efficient photosensitizer for photodynamic therapy. Under illumination, NGODs produce a considerable amount of H2O2 in the presence of physiological levels of H2Asc as a hole scavenger and further enhance the therapeutic efficiency. Thus, a concise nanotherapeutic modality could be achieved through the conjunction of multifunctional NGODs and H2Asc to selectively eliminate deep-seated and superficial tumors simultaneously (under 65% of normal cell viability, it kills almost all cancer cells). Note that this level of therapeutic versatility generally requires multiple components and complex manufacturing processes that run into difficulties with FDA regulations and clinical applications. In this study, the concise NGOD-H2Asc nanotherapeutic modality has demonstrated its great potential in cancer therapy.

Synthesis and analysis of nanostructured graphene oxide

Work has been carried out to improve the method for obtaining and further oxidizing Graphene Oxide (GO) to obtain functionalized layers with a large number of active centres. We have determined that with an increase in the amount of H2O2 in the synthesis, it significantly increases the efficiency of the oxidation process and increases the number of functional groups, while the amount of NaNO3 and KMnO4 remains unchanged. Fourier-Transform Infrared Spectroscopy (FTIR), X-ray analysis, Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses were carried out. Based on the FTIR result, all putative functional groups for a given material (GO) were determined, such as carbonyl, hydroxyl, ketone and epoxy groups which chemically bonded with graphene. SEM and TEM drawings were analysed, which gave a broad understanding of the morphology of GO nanostructures and, based on these drawings, it is fashionable to say that the material is semi-crystalline with the presence of such byproducts as amorphous carbon nanoparticles. Based on the EDX analysis, it was proved that this nano-structured material does not have third-party products.

Evaluation of the effect of peptidoglycan-constituting components on photocatalytic bactericidal sterilization.

Previous studies in our lab have shown that peptidoglycan (PG) enhances the photocatalytic bactericidal effect. Therefore, in this study, we focused on the PG-constituting components. The PG-constituting components were added to Mesoplasma florum with no cell wall, respectively, and their effects on photocatalytic sterilization were investigated. The PG-constituting components used were amino sugars, amino acids, L-Alanine-D-Glutamic Acid (L-Ala-D-Glu) dipeptide of diaminopimelic acid (DAP）-type crosslinking peptide, and Lysine (Lys）-type crosslinking peptide. We compared the survival rates of M. florum cells and PG-constituting components-added M. florum cells after 3 h of photocatalytic reaction. Consequently, the survival rates of the cells that were added N-acetylglucosamine (GlcNAc）, DAP, and L-Ala- D-Glu dipeptide were significantly lower than those of only the cells. Furthermore, the amounts of hydrogen peroxide (H2O2) generated by the photocatalytic reaction under the presence of these components were determined. The results showed that DAP, L-Ala- D-Glu dipeptide, and PG of DAP-type significantly increased the amount of H2O2 produced. From the above results, it is suggested that the presence of DAP and L-Ala- D-Glu dipeptide in the photocatalytic reaction boosts the production of H2O2 and enhances the bactericidal effect and that GlcNAc might produce reactive oxygen species other than H2O2.

Treatment of Dairy Wastewater with Pretreatment Techniques and Sequencing Batch Reactor for the Removal of Pollutants: Kinetics and Optimization

In order to remove pollutants like BOD, COD, TKN, TP, TSS, sulphates, chlorides, oil and grease effectively, this study outlines the treatment of dairy effluent by employing the advanced oxidation process (AOP) as pretreatment method with a sequencing batch reactor. It also describes the impact of aeration time and bacterial mass concentration (MLSS) in the sequencing batch reactor for pollutant removal. The high percentage of nutrient contents can be removed by the sequencing batch reactor (SBR), which only needs a single tank for the entire treatment procedure. The pretreatment technique of a combination of ozone and AOP was introduced into the dairy effluent to increase the removal efficiency of pollutants. In this research, the optimal conditions for ozone were a pH of 10, a reaction time of 5 minutes, and an amount of H2O2 of 10 mL/L. The experiments were conducted in the 4 L Plexiglas reactor and the analysis was carried out for different aeration times of 4, 6, 8, 12, 16 and 24 h at the different MLSS concentrations of 2100, 2400, 2900, 3200, 3700 and 4200 mg/L after the addition of ozone and hydrogen peroxide. In this analysis, the higher percent removal of BOD, COD, TKN, TP, TSS, sulphates, chlorides, oil and grease was obtained for the MLSS of 2100 mg/L at the aeration time of 16 h. The percent removal of above pollutants for the above MLSS concentration was in the order of 99.8%, 99.6%, 76.7%, 99%, 99.3%, 34%, 46% and BDL, respectively. The GC-MS analysis was carried out to find the level of contaminants present in the raw and treated water. Further, the sludge analysis was done for the wasted sludge to find its characteristics and its uses. This study suggests that at low MLSS concentrations, a large percentage of pollutants can be removed.

Determination of Salt Tolerance of Some Barley Varieties Based on Physiological and Biochemical Properties

Salt stress is one of the important environmental factors limiting the growth and productivity of barley (Hordeum vulgare L.) worldwide. Increasing salt stress negatively affects plant growth and development, posing a threat to global food security. In this study, some physiological and biochemical effects of salt stress at different concentrations (0, 50, 100, 200 mM NaCl) on 8 barley varieties (Kıral-97, Harman, Yaprak, Yaba, Larende, Cumhuriyet-50, Kalaycı-97, Çıldır-02) grown in Turkey were determined. For this purpose, the effects of salt stress on root-shoot length, biomass, pigment content, specific leaf area (SLA), relative water content (RWC), lipid peroxidation content (TBARS), hydrogen peroxide (H2O2) (spectrophotometric and histochemical staining) content were determined in 35-day-old seedlings. Our results showed that increased salt stress decreased the root-shoot lengths, biomass, SLA, and pigment contents in Cumhuriyet-50 and Çıldır-02 varieties, while increasing the amount of TBARS and H2O2. It was determined that Yaprak and Yaba varieties were less affected by salt stress and were more resistant to salinity compared to other varieties.

Defect Engineering of Porous g-C3N4 to Add Multifunctional Groups for Enhanced Production of H2O2 via Piezo-Photocatalysis

Hydrogen peroxide (H2O2) plays an essential role in many industrial fields and is globally listed as one of the indispensable chemicals. However, synthesizing H2O2 using the anthraquinone oxidation (AO) process requires multiple steps and releases hazardous organic compounds, which could seriously lead to many environmental and human health-related problems. Therefore, an urgent need for manufacturing H2O2 using green and sustainable methods to deal with the mentioned issues has enormously captured scientific interest. In this circumstance, the integration of piezo and photo effects on the generation of H2O2 from water and oxygen with the requirements of using low-cost and efficient catalytic materials is majorly considered. Herein, we report a simple and efficient way to produce H2O2 by employing modified graphitic carbon nitride (g-C3N4) catalysts to achieve the targets. The nanostructured materials were intensively characterized to deeply understand how the catalysts work to produce a significant amount of H2O2, reaching up to 1147.03 μM within 1 h irradiation. The findings showed that the fabrication of novel metal–carbon bonds and other functional groups could be responsible for adding more active sites in the system, promoting the enhancement of catalytic activities. This work would offer scientists a novel outlook to design and develop carbon-based materials for producing fine chemicals from catalysis and other applications.

Effects of Different Priming Treatments on Germination and Seedling Growth of Wheat under Drought Stress

Wheat (Triticum aestivum L.) is a widely cultivated agricultural crop in dry areas. However, drought is one of the most limiting environmental stress factors for crop production in the world's agricultural areas. Seed priming is a physiological technique involving seed hydration and drying to improve metabolic processes before germination. The aim of this study is to determine the effect of four different priming treatments (hormo-priming (gibberellic acid, GA3), redox-priming (hydrogen peroxide, H2O2), osmo-priming (polyethylene glycol, PEG) and thermo-priming (38oC)) on total chlorophyll content (SPAD), relative water content (RWC), specific leaf area (SLA), H2O2 amounts and shoot-root lengths in a local wheat variety (cv. Ekiz). Drought stress significantly decreased seed germination, shoot-root lengths, SLA, SPAD and RWC while increasing H2O2 content. Thermo-priming treatments fully improved the negative effects of drought on chlorophyll amount and germination compared to control plants. However, shoot-root lengths improved only in half level of control plants. While drought stress decreased seed germination by 14%, hormo-priming treatment ensured germination of all seeds. On the contrary of other priming treatments, hormo-priming and osmo-priming treatments increased RWC. Consequently, thermo-priming and hormo-priming treatments found most effective than the other priming treatments in drought stress resistance for cv. Ekiz.

Improved esthetic efficacy and reduced cytotoxicity are achieved with a violet LED irradiation of manganese oxide-enriched bleaching gels.

Gels with high concentrations of hydrogen peroxide (H2O2) have been associated with cytotoxicity and consequent post-bleaching tooth sensitivity. This study assessed the bleaching efficacy (BE) and cytotoxicity (CT) of bleaching gels with low concentrations of H2O2 containing manganese oxide (MnO2) and photocatalyzed with violet LED (LEDv). The following groups were established: G1: no treatment (negative control, NC); G2: 35% H2O2 (positive control, PC); G3: LEDv; G4: 10% H2O2; G5: 6% H2O2; G6: 10% H2O2 + MnO2 + LEDv; G7: 6% H2O2 + MnO2 + LEDv. To analyze BE, standardized enamel/dentin discs (E/DDs) were subjected to the bleaching procedures for 45min (1 session). The color change was determined before and after performing the bleaching protocols (ΔE00; ΔWI). To analyze CT, the E/DDs were adapted to artificial pulp chambers, and the extracts (culture medium + diffused gel components) were applied to cultured odontoblast-like MDPC-23 cells. Then, the cells were assessed concerning their viability (VB), oxidative stress (OxS), and Live/Dead. The amount of H2O2 diffused was also determined (ANOVA/Tukey; p < 0.05). Cell viability decreased in all bleached groups compared to G1 (NC; p < 0.05). The cells in G6 and G7 presented higher viability than in G2, G4, and G5 (p < 0.05). The BE in G7 was similar to G2 (PC; p < 0.05). The lowest OxS and H2O2 diffusion values were found in G6 and G7, compared to the other bleached groups (G2, G4, and G5; p < 0.05). The 6% H2O2 bleaching gel (G7) submitted to both methods of catalysis (MnO2 + LEDv) caused only a mild cytotoxicity and maintained the excellent esthetic outcome promoted by in-office conventional tooth bleaching.

H2 O2 feeding enables LPMO-assisted cellulose saccharification during simultaneous fermentative production of lactic acid.

Simultaneous saccharification and fermentation (SSF) is a well-known strategy for valorization of lignocellulosic biomass. Because the fermentation process typically is anaerobic, oxidative enzymes found in modern commercial cellulase cocktails, such as lytic polysaccharide monooxygenases (LPMOs), may be inhibited, limiting the overall efficiency of the enzymatic saccharification. Recent discoveries, however, have shown that LPMOs are active under anoxic conditions if they are provided with H2 O2 at low concentrations. In this study, we build on this concept and investigate the potential of using externally added H2 O2 to sustain oxidative cellulose depolymerization by LPMOs during an SSF process for lactic acid production. The results of bioreactor experiments with 100 g/L cellulose clearly show that continuous addition of small amounts of H2 O2 (at a rate of 80 µM/h) during SSF enables LPMO activity and improves lactic acid production. While further process optimization is needed, the present proof-of-concept results show that modern LPMO-containing cellulase cocktails such as Cellic CTec2 can be used in SSF setups, without sacrificing the LPMO activity in these cocktails.

Fe2O3/diatomite materials as efficient photo-Fenton catalysts for ciprofloxacin removal.

In this study, we used Fe2O3/diatomite material system toward ciprofloxacin (CIP) photo-Fenton removal in water under visible light (vis) excitation. The characterization of Fe2O3/diatomite catalysts was determined by X-ray diffraction patterns, Fourier-transform infrared analysis, inductively coupled plasma mass spectrometry, and scanning electron microscopy. The photo-Fenton catalytic activity of the Fe2O3/diatomite was appraised by the removal efficiency of the CIP throughout the effect of the H2O2 with various parameters such as initial pH, catalyst amount, and H2O2 amount. The results indicate that 0.2 gL-1 Fe2O3/diatomite catalysts achieved the highest performance at approximately 90.03% with a 50 μL H2O2 concentration. Furthermore, the Fe2O3/diatomite catalysts have high stability, with over 80% CIP removed after five cycles. This study is inspired to develop a potential material for photo-Fenton degradation of antibiotics in wastewater.

Boosting ROS-Mediated Lysosomal Membrane Permeabilization for Cancer Ferroptosis Therapy.

Due to the deficient catalase, abundant reduced iron and low acidic environment in lysosomes, inducing lysosomal membrane permeabilization (LMP) through Fenton reaction-based reactive oxygen species (ROS) generation recently attracts increasing attention in cancer therapy. However, the lysosomal membranes are protected by highly glycosylated membrane proteins and several endolysosomal damage-response mechanisms can rapidly repair the injured lysosomes. To produce sufficient ROS and cause complete lysosomal membranes rupture, a lysosome-targeted ROS inducer, N-(3-Aminopropyl) morpholine grafted cross-linked lipoic acid vesicles with vitamin C-loading (VC@N3AM cLAVs), is developed. VC@N3AM cLAVs efficiently accumulate in lysosomes and convert into two redox couples LA/DHLA (dihydrolipoic acid, reduced form of LA) and VC/DHA (dehydroascorbic acid, oxidized form of VC) by the lysosomal glutathione, which can not only produce a large amount of H2 O2 by pro-oxidant action but also accelerate iron transformation through the cyclic redox reactions between each other and cause the efficient conversion of the generated H2 O2 into highly toxic •OH. Both in vitro and in vivo experiments demonstrate that VC@N3AM cLAVs can effectively enhance ROS production and boost LMP, finally initiation irreversible death of tumor cells via ferroptosis pathway, thus representing a potential anticancer drug for cancer therapy.

Dual-responsive disassembly of core-shell nanoparticles with self-supplied H2O2 and autocatalytic Fenton reaction for enhanced chemodynamic therapy

Chemodynamic therapy holds great potential for cancer treatment due to its reliable curative effects, minimal invasiveness, and few systemic side effects. However, the limited amount of intracellular H2O2 makes achieving high-performance chemodynamic therapy challenging. Herein, we report a core-shell nanoplatform with dual-responsive disassembly that self-supplies H2O2 and undergoes an autocatalytic Fenton reaction for enhanced chemodynamic therapy. The platform was designed by coating glucose oxidase-mimicking nanozyme gold nanoparticles (AuNPs) with a metal-polyphenol network (Au@MPN). Both ATP and low pH can disassemble the Au@MPN to release Fe(III), which can then be reduced into Fe(II) by the simultaneously released tannic acid (TA). In particular, the exposed AuNPs can catalyze the oxidation of intracellular glucose to produce H2O2. Subsequently, Fe(II) and the self-supplied H2O2 induce an efficient Fenton reaction for chemodynamic therapy by generating hydroxyl radicals (•OH) that are highly toxic to cancer cells. Moreover, tumor growth can be effectively suppressed after both intratumoral and intravenous Au@MPN administration. Additionally, metastatic melanoma lung tumors could be inhibited by intratracheal instillation of Au@MPN. Thus, this work not only reports a facile method to construct a chemodynamic agent with self-supplied H2O2 and high therapeutic efficiency but also provides insight into the design of nanoplatforms with enhanced efficiency for chemodynamic therapy.

Using a novel gas diffusion electrode based on PL6 carbon modified with benzophenone for efficient H2O2 electrogeneration and degradation of ciprofloxacin

The present study reports the development and application of a gas diffusion electrode (GDE) based on Printex L6 carbon modified with 2.0% benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (PL6C/2.0%BTDA) for the efficient electrogeneration of hydrogen peroxide (H2O2) and degradation of ciprofloxacin (CIP) using different advanced oxidation processes (AOPs). The modified GDE was studied under different current densities and 25 mA cm−2 was found to be the most efficient current density, since the application of the modified GDE at this current density yielded higher amounts of H2O2, greater kinetic constant and lower energy consumption compared to unmodified GDE. Based on these results, the modified GDE was used for the degradation of CIP in alkaline solutions using different AOPs, including anodic oxidation (AO), UVC photolysis, and processes based on H2O2 electrogeneration (AO/e-H2O2/UVC and AO/e-H2O2). The AO/e-H2O2/UVC technique was found to be the most efficient among the AOPs investigated; the application of this technique led to the complete removal of CIP (75 µmol L–1) in 20 min of treatment, apart from yielding the highest kinetic constant rate and lower electrical energy per order (2.1 kWh m−3 order–1). The oxidation by-products generated during CIP degradation via AO/e-H2O2/UVC were successfully identified and a pathway for CIP degradation was proposed.

Kinetics of copper leaching from direct-to-blister copper flash smelting slag by sulfuric acid

Coppermaking from sulfide concentrates entails two major steps: smelting and converting. In continuous direct-to-copper smelting process these two steps are combined into one. The principal advantages of this process are: isolation of SO2 emission to a single, continuous, SO2-rich gas stream, minimization of energy consumption and minimization of capital and operating costs. Disadvantages of the process are that about 25% of the Cu entering a direct-to-copper smelting furnace ends up dissolved in the slag (when compared with < 10% in traditional Peirce–Smith converting) and the cost of recovering this Cu is significant. Decopperization process is based on the reduction of cuprous oxide and other metals, mainly lead and iron, in the liquid state in an electric furnace in the presence of coke and technological additives. This paper presents the results of laboratory tests on flash smelting slag leaching with sulfuric acid solutions. Hydrometallurgical treatment of the slag could be an alternative route to the presently used way of processing. The influence of a number of leaching parameters such as sulfuric acid concentration, amount of H2O2 added, liquid to solid phase (l/s) parameter and process temperature on the copper leaching efficiency was investigated. Under optimized process conditions, 95.6% of the copper contained in the original sample of slag was transferred into a solution. The experimental results obtained in the study were supplemented with the analysis of the kinetics of the copper leaching process from the flash smelting slag. The commonly known from the literature diffusion model and chemical reaction model were used. The activation energy of copper leaching from flash smelting slag was estimated in the range from 12.77 to 17.34 kJ/mol.

3D heteroatom-doped graphene-wrapped flexible carbon fiber microsensor for real-time hydrogen peroxide detection in live cancer cells

Balancing electrostatic repulsive force and bonding interactions are the key principles for constructing 3D graphene architecture on single carbon fiber (CF). Herein, we present a simple and facile method to modify 3D porous N, B co-doping graphene on single CF (CF@3D-NBG). In the process, the Ni nanoparticles were deposited on CF and used as a reductant for reducing graphene oxide (GO), promising graphene-wrapped CF at low temperature. Ionic liquids were introduced to prevent re-aggregation of graphene sheets during the reduction process of GO, but also acted as heteroatom sources for doping graphene, which provides high electrical conductivity, numerous doping sites and edges for H2O2 electrocatalysis reduction. It is found that the CF@3D-NBG flexible microelectrodes show a broad linear range from 0.5 μM to 4.25 mM and a low detection limit of 100 nM for H2O2 detection. When applied to track the amount of H2O2 generated from real samples, the sensor exhibits desirable performance in distinguishing cancer cells from normal cells and further assessing the therapeutic effect of antitumor drugs on live cancer cells. Therefore, this study may offer an attractive method for synthesizing advanced graphene-based electrodes with great promise for biosensors.

Loss of chloroplast-localized NAD kinase causes ROS stress in Arabidopsis thaliana.

Chloroplast-localized NAD kinase (NADK2) is responsible for the production of NADP+, which is an electron acceptor in the linear electron flow of photosynthesis. The Arabidopsis T-DNA-inserted mutant of NADK2 (nadk2) showed delayed growth and pale-green leaves under continuous light conditions. Under short-day conditions (8h light / 16h dark), the nadk2 mutant showed more severe growth inhibition.The genomic fragment containing the promoter and coding region of NADK2 complemented the phenotypes of nadk2 obtained under continuous light and short-day conditions. The nadk2 mutant produced higher amounts of H2O2 and O2-, which were reduced in the complementary line. Under short-day conditions, the nadk2 mutant accumulated more H2O2 than under continuous light conditions. The accumulation of ascorbate and up-regulation of the PDF1.2 and PR1 genes indicated that the nadk2 mutant is under ROS stress and responding to keep its living activities.